Chemical reactions occur when elements or compounds combine and create new compounds. Elements are substances that contain only one type of atom and are represented by unique symbols on the periodic ...

Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...

Everything that has mass and which occupies space is called 'matter'. The universe is constructed with matter and energy. Matter is made of very small particles and is constantly dynamic. It is ...